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[one_wire][dallas_temp] adjust timings and reduce disabled interrupts (#8744)

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Co-authored-by: Samuel Sieb <samuel@sieb.net>
This commit is contained in:
Samuel Sieb
2025-05-11 14:33:50 -07:00
committed by GitHub
parent cdc1a7c646
commit 04147a7f27
6 changed files with 92 additions and 87 deletions
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88
esphome/components/gpio/one_wire/gpio_one_wire.cpp
View File

@@ -10,8 +10,10 @@ static const char *const TAG = "gpio.one_wire";
void GPIOOneWireBus::setup() {
ESP_LOGCONFIG(TAG, "Setting up 1-wire bus...");
this->t_pin_->setup();
// clear bus with 480µs high, otherwise initial reset in search might fail
this->t_pin_->pin_mode(gpio::FLAG_INPUT | gpio::FLAG_PULLUP);
// clear bus with 480µs high, otherwise initial reset in search might fail
this->pin_.digital_write(true);
this->pin_.pin_mode(gpio::FLAG_OUTPUT);
delayMicroseconds(480);
this->search();
}
@@ -22,40 +24,49 @@ void GPIOOneWireBus::dump_config() {
this->dump_devices_(TAG);
}
bool HOT IRAM_ATTR GPIOOneWireBus::reset() {
int HOT IRAM_ATTR GPIOOneWireBus::reset_int() {
InterruptLock lock;
// See reset here:
// https://www.maximintegrated.com/en/design/technical-documents/app-notes/1/126.html
// Wait for communication to clear (delay G)
pin_.pin_mode(gpio::FLAG_INPUT | gpio::FLAG_PULLUP);
this->pin_.pin_mode(gpio::FLAG_INPUT | gpio::FLAG_PULLUP);
uint8_t retries = 125;
do {
if (--retries == 0)
return false;
return -1;
delayMicroseconds(2);
} while (!pin_.digital_read());
} while (!this->pin_.digital_read());
bool r;
bool r = false;
// Send 480µs LOW TX reset pulse (drive bus low, delay H)
pin_.pin_mode(gpio::FLAG_OUTPUT);
pin_.digital_write(false);
this->pin_.digital_write(false);
this->pin_.pin_mode(gpio::FLAG_OUTPUT);
delayMicroseconds(480);
// Release the bus, delay I
pin_.pin_mode(gpio::FLAG_INPUT | gpio::FLAG_PULLUP);
delayMicroseconds(70);
this->pin_.pin_mode(gpio::FLAG_INPUT | gpio::FLAG_PULLUP);
uint32_t start = micros();
delayMicroseconds(30);
while (micros() - start < 300) {
// sample bus, 0=device(s) present, 1=no device present
r = !this->pin_.digital_read();
if (r)
break;
delayMicroseconds(1);
}
// sample bus, 0=device(s) present, 1=no device present
r = !pin_.digital_read();
// delay J
delayMicroseconds(410);
return r;
delayMicroseconds(start + 480 - micros());
this->pin_.digital_write(true);
this->pin_.pin_mode(gpio::FLAG_OUTPUT);
return r ? 1 : 0;
}
void HOT IRAM_ATTR GPIOOneWireBus::write_bit_(bool bit) {
// drive bus low
pin_.pin_mode(gpio::FLAG_OUTPUT);
pin_.digital_write(false);
this->pin_.digital_write(false);
// from datasheet:
// write 0 low time: t_low0: min=60µs, max=120µs
@@ -64,72 +75,62 @@ void HOT IRAM_ATTR GPIOOneWireBus::write_bit_(bool bit) {
// recovery time: t_rec: min=1µs
// ds18b20 appears to read the bus after roughly 14µs
uint32_t delay0 = bit ? 6 : 60;
uint32_t delay1 = bit ? 59 : 5;
uint32_t delay1 = bit ? 64 : 10;
// delay A/C
delayMicroseconds(delay0);
// release bus
pin_.digital_write(true);
this->pin_.digital_write(true);
// delay B/D
delayMicroseconds(delay1);
}
bool HOT IRAM_ATTR GPIOOneWireBus::read_bit_() {
// drive bus low
pin_.pin_mode(gpio::FLAG_OUTPUT);
pin_.digital_write(false);
this->pin_.digital_write(false);
// note: for reading we'll need very accurate timing, as the
// timing for the digital_read() is tight; according to the datasheet,
// we should read at the end of 16µs starting from the bus low
// typically, the ds18b20 pulls the line high after 11µs for a logical 1
// and 29µs for a logical 0
uint32_t start = micros();
// datasheet says >1µs
delayMicroseconds(2);
// datasheet says >= 1µs
delayMicroseconds(5);
// release bus, delay E
pin_.pin_mode(gpio::FLAG_INPUT | gpio::FLAG_PULLUP);
// measure from start value directly, to get best accurate timing no matter
// how long pin_mode/delayMicroseconds took
uint32_t now = micros();
if (now - start < 12)
delayMicroseconds(12 - (now - start));
this->pin_.pin_mode(gpio::FLAG_INPUT | gpio::FLAG_PULLUP);
delayMicroseconds(8);
// sample bus to read bit from peer
bool r = pin_.digital_read();
bool r = this->pin_.digital_read();
// read slot is at least 60µs; get as close to 60µs to spend less time with interrupts locked
now = micros();
if (now - start < 60)
delayMicroseconds(60 - (now - start));
// read slot is at least 60µs
delayMicroseconds(50);
this->pin_.digital_write(true);
this->pin_.pin_mode(gpio::FLAG_OUTPUT);
return r;
}
void IRAM_ATTR GPIOOneWireBus::write8(uint8_t val) {
InterruptLock lock;
for (uint8_t i = 0; i < 8; i++) {
this->write_bit_(bool((1u << i) & val));
}
}
void IRAM_ATTR GPIOOneWireBus::write64(uint64_t val) {
InterruptLock lock;
for (uint8_t i = 0; i < 64; i++) {
this->write_bit_(bool((1ULL << i) & val));
}
}
uint8_t IRAM_ATTR GPIOOneWireBus::read8() {
InterruptLock lock;
uint8_t ret = 0;
for (uint8_t i = 0; i < 8; i++) {
for (uint8_t i = 0; i < 8; i++)
ret |= (uint8_t(this->read_bit_()) << i);
}
return ret;
}
uint64_t IRAM_ATTR GPIOOneWireBus::read64() {
InterruptLock lock;
uint64_t ret = 0;
for (uint8_t i = 0; i < 8; i++) {
ret |= (uint64_t(this->read_bit_()) << i);
@@ -144,6 +145,7 @@ void GPIOOneWireBus::reset_search() {
}
uint64_t IRAM_ATTR GPIOOneWireBus::search_int() {
InterruptLock lock;
if (this->last_device_flag_)
return 0u;

3
esphome/components/gpio/one_wire/gpio_one_wire.h
View File

@@ -18,7 +18,6 @@ class GPIOOneWireBus : public one_wire::OneWireBus, public Component {
this->pin_ = pin->to_isr();
}
bool reset() override;
void write8(uint8_t val) override;
void write64(uint64_t val) override;
uint8_t read8() override;
@@ -31,10 +30,12 @@ class GPIOOneWireBus : public one_wire::OneWireBus, public Component {
bool last_device_flag_{false};
uint64_t address_;
int reset_int() override;
void reset_search() override;
uint64_t search_int() override;
void write_bit_(bool bit);
bool read_bit_();
bool read_bit_(uint32_t *t);
};
} // namespace gpio